Abstract: The aim of this study was to evaluate the effects of composite antimicrobial peptide (AMP) on rumen bacteria community structure by MiSeq high throughput sequencing technology, which could provide theoretical basis for the application of antimicrobial peptide in ruminant. Twenty-four male goats (4-month-old) were randomly divided into 4 groups according to the similar weight. Four groups were normal concentrate group A (concentrate 300 g·d^-1·goat^-1), normal concentrate+AMP group C (concentrate 300 g·d^-1·goat^-1 + AMP 3 g·d^-1·goat^-1), double concentrate group D (concentrate 600 g·d^-1·goat^-1), double concentrate + AMP group E (concentrate 600 g·d^-1·goat^-1 + AMP 3 g·d^-1·goat^-1). The rumen fluid samples were collected after 20 d, and then the total DNA were extraced for amplification 16S rRNA(520F-802R), sequencing by MiSeq Illumina250. Results showed as follows: 1) A total of 629 634 valid 16S rDNA sequences and 13 227 operational taxonomic unit (OTU) across 12 samples were obtained. 2) At phylum level, Bacteroidetes was the most abundant phyla in A, C and E groups (38.52%-43.68%), except for the D group (Firmicutes was the most abundant phyla, 34.30%), and Proteobacteria and Spirochaetes were significantly decreased when adding AMP (P<0.05); Firmicutes and Spirochaetes were significantly increased in D group compared with A group(P<0.05), while Bacteroidetes and Proteobacteria were significantly decreased (P<0.05). 3) At genus level, Prevotella was the most abundant genus in all samples (25.54%-33.88%), Succiniclasticum, Ruminococcus, Pseudobutyrivibrio and Desulfovibrio were significantly increased when adding AMP (P<0.05 or P<0.01), while Succinivibrio was extremely significantly decreased (P<0.01), and it was not affected by the amount of concentrate; But the change tendency of Selenomonas and Treponema were affected by the amount of concentrate when adding AMP, significantly decreased in C group compared with A group (P<0.05), but no significant difference between D and E groups (P>0.05). Prevotella and Treponema were significantly increased in D group compared with A group (P<0.05), while Succinivibrio was significantly decreased (P<0.05). 4) There were no significant differences (P>0.05) between groups on alpha diversity index (Chao, ACE, Shannon and Simpson). In conclusion, Proteobacteria and Spirochaetes were decreased when adding complex antibacterial peptide, while some genus of cellulolytic were increased; Firmicutes and Spirochaetes were increased when the amount of concentrate changed from 300 to 600 g·d^-1·goat^-1, while Bacteroidetes and Proteobacteria were decreased, and Prevotella was increased, while Succinivibrio was decreased. Moreover alpha diversity index was not affected by complex antibacterial peptide or the amount of concentrate changed from 300 to 600 g·d^-1·goat^-1.

Key words: goat, rumen bacteria, community structure, high-throughput sequencing, composite antimicrobial peptide, concentrate